After a long winter, many people look forward to spending time outdoors in the summer warmth. But excessive exposure to high temperatures and humidity, or performing strenuous activities during hot weather, may result in life-threatening heat-related illnesses. As with cold weather exposure, the elderly and young are most at risk. However, anyone can succumb to high heat exposure.

Two common hot-weather health emergencies are heat stroke and heat exhaustion.

Heat stroke occurs when the body loses its ability to regulate its internal temperature. The sweating mechanism (the body’s way of cooling itself) shuts down, and the body temperature rapidly rises—as high as 106ºF or more. Symptoms of heat stroke include:

  • high body temperature
  • hot skin with absence of sweating
  • headache
  • dizziness
  • nausea
  • rapid pulse
  • confusion
  • loss of consciousness

Heat stroke is a medical emergency. Medical help must be sought immediately, while efforts are taken to cool the person. These include moving him or her to a shady area and lowering the body temperature with cool (but not cold) water. This should be applied to the body with a sponge, wet towels, or sheets. Monitor the person’s temperature until medical help arrives. If the person has nausea, is vomiting, or is unconscious, do not attempt to give fluids.

Heat exhaustion is a milder form of heat-related illness than heat stroke. It develops more slowly, and may occur after several days of heat exposure and inadequate fluid replacement. Symptoms of heat exhaustion include:

  • profuse sweating
  • dizziness
  • weakness
  • headache
  • nausea or vomiting
  • fatigue
  • muscle cramps

If not treated, heat exhaustion can progress to heat stroke. If symptoms are severe or the person has a heart condition, medical attention should be summoned while cooling efforts begin. Cool the body as you would do for heat stroke, and offer cool, nonalcoholic beverages to drink. If symptoms persist longer than an hour, seek medical treatment.

Heat-related illness is preventable. Here’s what to do to stay safe in hot weather:

  • Listen to weather reports for heat advisories. Stay indoors, ideally in air conditioning, as much as possible and during the afternoon when temperatures are at their highest. People older than 65 who are at high risk for heat-related illnesses should be especially mindful..
  • Dress for the weather in lightweight, light-colored, loose clothing. Cover as much skin as possible with proper clothing and a hat, or use an umbrella. Apply sunscreen with an SPF of at least 15, and continue to apply it according to label directions.
  • Eat lighter meals; heavy meals can increase your core body temperature.
  • Save strenuous outdoor activities for the cooler morning hours, if at all possible.
  • Don’t wait until you feel thirsty to drink. Increase your fluid intake, even if you’re inactive. If you are working or playing outdoors, you need to consume two to four glasses of water every hour. If you sweat, some of this fluid can come from sports beverages, which will help to replace salt and minerals lost through sweat. (Those who are on fluid or salt restrictions should consult a medical professional for advice about fluid replacement and sports drinks.)
  • Learn the symptoms of heat exhaustion and heat stroke. If you recognize early symptoms of heat-related illness in yourself or another person, move indoors or at least to a shady area, drink cool fluids, and rest.